Gretsch Expandafuzz

[tcobretti]

Thanks huge, Mike!!

[Austin73]

Cheers for the schem Mike.

What are the IC's used?

RG you up for doing a layout still? lol

Thanks everyone for jumping on this

Aus

[tommy.genes]

Thanks for posting the schemo, Mike.

Notable points based on first-glance analysis:

• The Expandatone circuit is completely after the Controfuzz.
• The Expandatone is still "in" the circuit even when the Controfuzz is bypassed.
• Mark H. was right about it being three parallel EQ circuits.
• The TREBLE, MID-RANGE and BASS switches don't really "remove" the EQ circuits, but instead effectively turn the knob to the lowest setting.

I'll continue to look at the circuit once I'm back in the office next week (when else do I have that much "free" time?), and I look forward to any further insights from Mark, R.G. and others.

[edit for typos]

-- T. G. --

[antojado]

General Guitar Gadgets has a schem. and layout for the controfuzz so you could start with that and modify it or build another board to add to it.
http://www.generalguitargadgets.com/pdf/ggg_controfuzz.pdf

The GGG file says the original ic was an LM748, but this schem. says UA748. http://www.cirlab.uniroma2.it/Courses/TC_TechSup/doc/DataSheet/slos095.pdf

Here's another schem. of the controfuzz: http://www.freeinfosociety.com/electronics/schematics/audio/gretschcontrofuzz7798.pdf

[Rob Dobbs]

Im not eager to tear apart my favorite pedal but if there is an experianced builder in the south bay los angeles area drop me a pm.

[John Lyons]

So where to the "TP1, 2,3 and 4 points connect?
Oh, maybe Test Points?

[andy-h-h]

So where to the "TP1, 2,3 and 4 points connect?
Oh, maybe Test Points?

Bit late to the party as they say....    I was having a look at this today on spice, and spent some time looking at the photos of circuit boards posted.   The 10k resistors from the opamp outputs to TP points don't appear to connect to anything. 

I'd say you're right.  Just test points.